# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
%YAML 1.2
---
$id: http://devicetree.org/schemas/i2c/i2c-mux-reg.yaml#
$schema: http://devicetree.org/meta-schemas/core.yaml#

title: Register-based I2C Bus Mux

maintainers:
  - Peter Rosin <peda@axentia.se>

description: |
  This binding describes an I2C bus multiplexer that uses a single
  memory-mapped register to route the I2C signals.

  Whenever an access is made to a device on a child bus, the value
  set in the relevant node's reg property is output to the register.

  If an idle state is defined via the idle-state property, the
  register is set to that value whenever no access is being made.
  Otherwise the most recently used value is left programmed.

allOf:
  - $ref: /schemas/i2c/i2c-mux.yaml#

properties:
  compatible:
    const: i2c-mux-reg

  reg:
    maxItems: 1
    description: |
      Offset and size of the register that selects the active child
      bus, relative to the parent node's address space. The size
      determines the access width and must be 1, 2, or 4 bytes. If
      omitted, the platform device's own memory resource is used
      instead.

  i2c-parent:
    $ref: /schemas/types.yaml#/definitions/phandle
    description:
      Phandle of the I2C bus that this multiplexer's master-side port
      is connected to.

  little-endian:
    type: boolean
    description: Register is accessed in little-endian byte order.

  big-endian:
    type: boolean
    description: Register is accessed in big-endian byte order.

  write-only:
    type: boolean
    description:
      Register is write-only; the driver must not read back the
      current selection.

  idle-state:
    $ref: /schemas/types.yaml#/definitions/uint32
    description:
      Value to write to the register when no child bus is selected.

required:
  - compatible
  - i2c-parent

unevaluatedProperties: false

examples:
  - |
    i2c-mux@6028 {
        compatible = "i2c-mux-reg";
        reg = <0x6028 0x4>;
        little-endian;
        #address-cells = <1>;
        #size-cells = <0>;
        i2c-parent = <&i2c1>;

        i2c@0 {
            reg = <0>;
            #address-cells = <1>;
            #size-cells = <0>;
        };

        i2c@1 {
            reg = <1>;
            #address-cells = <1>;
            #size-cells = <0>;
        };
    };
...